Mustard greens and dried oyster soup

Preparation

• Boil the water, blanch the ribs.
• Put everything inside.
• For normal pot, 4 cups of water, boil until 2.5 cups of water left after 2 hours.
• High heat for 10 mins then turn to simmering low heat till end.
• For pressure cooker, 3 cups of water in pressure cooker, 30 mins.